Cavity resonator electron discharge device



Feb. 20, 1951 W C, BROWN 2,542,899

CAVITY RESONATOR ELECTRON DISCHARGE DEVICE Filed Nov. 30, 1944 Als. if@

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Patented Feb. 20, 1951 CAVITY RESONATOR ELECTRON DISCHARGE DEVICE William C. Brown, Lincoln, Mass., assignor to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application November 30, 1944, Serial No. 565,925

This invention relates to electron discharge devices having a plurality of cavity resonators, and more particularly to those for generating oscillations of short Wave lengths.

As the power delivered by such a device is dependent upon the number of cavity resonators it contains, and as the wave length of the oscillations generated by a cavity resonator shorter or longer according as the cavity is smaller or larger, it follows that to obtain increased power with `a device for generating ultra-short waves will require a considerable increase in the number of cavity resonators contained in the device. Experience has shown, however, that there is a limit beyond which an increase in the number of cavity resonators is liable to give rise to objectionable phenomena, such as the generation of spurious oscillations, and a decrease in the effectiveness of cavities remote from the cavity coupled to the usual type of output coupling device, Very little, if any of the energy generated in' these remote cavities reaching said output coupling device.

One of the objects of the present invention is to enable the number of cavity resonators, and therefore the generation of power of short wave length in electron discharge devices of the general type referred to, to be materially increased without giving rise to the objectionable phenomena referred to.

Another object of the invention is to provide an electron discharge device of the aforesaid general type comprising a symmetrical coupling for all of the resonant cavities.

A further object of the present invention `is to provide an electron discharge device having an output coupling which shall exert its energy absorbent power equally with respect to each of the cavity resonators of the device.

These objects of the present invention and such other aims and objects thereof as may hereinafter appear will be best understood from the following description, taken in connection with the accompanying drawing of a short wave, high power generating electron discharge device incorporating one illustrative embodiment of the invention herein presented for illustrative purposes.

In the drawing:

Fig. l is a central, longitudinal section of said` Fig. 2 is a horizontal cross-section of thedevice on line 2--2 of Fig. 1; and

Fig. 3 is a perspective View showing the energy 9 Claims. (Cl. 315-40) absorbent part of the output coupling and how it cooperates with the resonant cavities.

The illustrative embodiment of the pre-sent invention shown comprises an anode structure including a cylindrical member 2 having upon its inner surface a central, cylindrical projection 4 to which are soldered a plurality of suitably spaced, radially disposed anode arms 5, the inner edge surfaces of which constitute anode faces 8- to receive electrons from the cathode. Each pair of said anode arms 6, with the intervening portion of said cylindrical projection 4, constitutes a cavity resonator I0. (See Fig. 2.) Said cylindrical member 2 is hermetically sealed at both ends, thus forming an hermetically sealed envelope or enclosure. In the illustrative embodiment of the invention shown, pole pieces I4 and I6 are con veniently used for this purpose, said pole pieces each conveniently comprising a cylindrical portion I8 terminating in a substantially conical portion 26 projecting into the opposite ends, respectively, of said cylindrical member 2. Each of said pole pieces comprises an axial bore 22 and said conical portions 2U are each encircled by a slot 24 rectangular in cross-section and engaged by the rectangular edge of the inner wall of said cylindrical member 2 to which it is soldered, preferably with silver solder, thus completing the hermetical sealing of the envelope. Said cylindrical member 2 and anode arms 5 will prefer ably be made of copper, said arms being conveniently stamped from a sheet of highly conductive copper. The aforesaid anode faces 8 co operate with a cathode 26 supported substantially centrally of said anode faces 8, said cathode being preferably of the indirectly heated, thermionic type and comprising a conductive wall 2t of nickel or other suitable conductive material, which may be coated with an electron-emissive 4coating of barium and strontium oxide orlother a glass seal 40, said sleeve 38 being soldered at its inner end to the outer end of said pole piece l. Said conductor 34 and said cathode support 3S are provided with axially aligned bores 42 and 44, respectively. A lead-in wire 46 extends axially of said bores and is connected at its outer end to a lead-in conductor 48, its inner end portion terminating in a helically Wound cathode heater Wire 5B contained within said cathode 26 and connected at its upper end to the interior surface of said conductive cathode sleeve 28. Said lead-in conductor 4S is sealed through a glass seal 52 in the outer end of a metal sleeve 54, the inner end of which is soldered to the reduced end 55 of said conductor 34. The lead-in conductor 48 thus serves to heat the cathode, while electrical connection to the cathode Wall may be made at conductor 36. Light, protectiveshields 58 of tantalum or other suitable metal may be provided at each end of said cathode `26 to prevent electron beams from being ,projected voutwardly toward said pole pieces i4 and I6 from said cathode. Said shields may be supported in any suitable manner. Herein said shields are conveniently made integral With said cathode Wall 28.

If the above described device he energized and a longitudinal magnetic field be excited within the device by suitable means, as for example by supplying said p ole pieces I4 and I6 with a magnetic iield froman external magnet, oscillations will be generated in the cavity resonators IU which Vmay be led out of the device to a suitable utilizing circuit by means comprising an output coupling device. l

The present invention contemplates the provision of novel means for this purpose, comprising an output coupling device which shall absorb the energy generated in the cavity resonators symmetrically from all of said cavities. In the illustrative-embodiment of the invention herein shown, said coupling conveniently comprises an electrically conductive member preferably of copper in the form of a circular cap Eil, Which engages alternate anode arms 6 at one end of the anode structure. The energy thus collected by said coupling cap S is led out through a coaxial line formed by a central conductor 62 and said pole piece M, said pole piece being copper-plated within the bore 22 for the purpose, whence it can be supplied to any suitable utilizing circuit.

through any suitable conventional wave guide or the like. Said central conductor G2 has its inner endelectrically connected to the center of said circular cap 60 by screw-threaded connection with the hub 64 of said cap, the other end of said conductor t2 being rsealed in a glass seal 66 hermetically sealed to one end of an electrically conductive sleeve 68 of suitable sealing metal, the other edge of said sleeve 68 being soldered to the upper edge of the axial bore 22 of said pole piece i4.

For the best results the dimensions of 'said coaxial line should be such as to produce a substantial impedance match between the tube and the load.

Said coupling cap 60, by its connection with alternate anode arms 6 at one end of the vanode structure, Vreplaces one of the straps, herein the inner strap Si), used to arrest the ygeneration of spurious oscillations. (See Fig. 3.)

arms at that end of the anode structure is shown at 10. At the other end of the anode structure those anode arms to which the coupling cap B0 is connected are connected by an outer strap '14, and the intervening arms to'which the strap I0 is connected are interconnected by yan `inner strap 12. ,i

In operation the polarityvof the anode arms fis constantly shifting, alternate anode arms being.V

The other or outer strap connecting the intervening anode i conductors. usedyapplicant obtains the same result as though Va separate coupling loop were provided within always of the opposite polarity to that of the in` tervening arms. By its connection With the alternate anode arms the coupling cap 60 carries on" the energy from all of said alternate arms to the conductor 62, while that from the intervening anode arms is carried off to Ythe pole piece I4, .said conductor and .said pole piece forming the central .and outer .conductors respectively of a coaxial line through which the energy collected by said coupling cap 60 is caused to flow out due to the difference of potential of said two By the simple, compact structure each .separate resonant cavity, but Without the complicated structure and planning such an arrangement would entail. Each cavity resonator `is 'connected directly' to the central coaxial conductor and not indirectly through one or more other cavity resonators. The coupling cap exerts its energy absorbentpower to its full capacity upon each of the resonant cavities;

Wherever the expression a plurality occurs, it is to be construedasmeaningtwo or more.

Igam aware that thepresent invention can be embodied in other specic forms without departing from the spirit or essential attributes thereof, and I therefore desire the ,present description to be considered in -all respects as illustrative and not restrictive,.reference being had to the appended claims rather than to the aforesaid description toindicate .the .scope of the invention.

What is claimed is: f

l. An .electron discharge .device comprising Van envelope hermetically sealed at both ends by, pole pieces and Icontaining .a cathode, an.:anode including a,plurality of anode 'arms having electron-receiving portions :adjacent .said cathode, and energy-generating cavityresonators .interconnecting saidelectron-receiving portions, electrically conductive straps .connecting alternate anode arms at each end of said anode, a conductor connectedto one of: said .straps and eX- -.tending axially'of abore. provided .axially in one of saidpole. pieces, said polepiece being electrically conductive, ssaidfconductor and .said rpole piece forming: the. centery conductor.Y andD the kouter conductor, respectively, `vof acoaxialline through -which oscillations generated by .the v.deviceimay necting, respectively, alternate .andintervening anode arms, said straps being concentrically .dis-

posed .and lying insa substantially commonzplane,

and an output .couplingincluding one of said straps. Y

3..Anelectron discharge device comprisingfa cathode, .an .anode including a' plurality of V.anode 'armshavingi electron'receiving portions adjacent said .,cathode, yenergy-generating cavity lresonators interconnecting said electron-receiving portions, a pair of electrically conductive :straps `connecting, respectively, alternate and intervening .anode arms-at each endfof said anode, the straps v at. each endrofV said anode being concentrically disposed and lyingin -a substantially common plane, ,and :an loutputfcouplingV including one -of said straps. Y

4. .An electronedischarge device vcomprising'l an hermetically sealed, electrically-conductive envelope containing a cathode and including an anode provided with a plurality of anode arms haw ing electron-receiving portions adjacent said cathode and energy-generating cavity resonators interconnecting said electron-receiving portions, an electrically conductive strap connecting alternate anode arms, a second electrically conductive strap connecting intervening anode arms, and a coaxial line comprising a center conductor and an outer conductor for conducting energy generated by the device out of the latter, said center conductor being connected to said conductive strap connecting alternate anode arms, and said outer conductor being connected to said intervening anode arms.

5. An electron discharge device comprising an hermetically sealed electrically-conductive envelope containing a cathode and including an anode including a plurality of alternate and intervening anode arms having electron-receivii1g portions adjacent said cathode and energy-generating cavity resonators interconnecting said electron-receiving portions, means for exciting a longitudinal magnetic eld within the device, an

electrically conductive strap connecting said alternate anode arms, and a coaxial line comprising a center conductor and an outer conductor for conducting energy generated by the device out of the latter, said center conductor being connected to said conductive strap, said outer conductor being connected to said intervening anode arms.

6. An electron discharge device comprising: a cathode, a hollow, open-ended anode, including a plurality of cavity resonators, surrounding said cathode, pole pieces hermetically sealed to said anode at the open ends thereof, and an output coupling engaging each of said cavity resonators.

7. An electron discharge device comprising: a cathode, a hollow, open-ended anode, including a plurality of cavity resonators, surrounding said cathode, pole pieces hermetically sealed to said anode at the open ends thereof, an energy absorbing member engaging each of said cavity resonators, and a conductor engaging said energy absorbing member and passing out of said device through a bore in one of said pole pieces.

8. `An'electron discharge device comprising: a cathode, a hollow, open-ended anode, including a plurality of cavity resonators, surrounding said cathode, pole pieces hermetically sealed to said anode at the open ends thereof, and an output coupling engaging each of said cavity resonators, one of said pole pieces being electrically conductive and dening, together with said output coupling, a transmission line. l

9. An electron discharge device comprising: a cathode, a hollow, open-ended anode, including a plurality of cavity resonators surrounding said cathode, pole pieces, one of which is electrically conductive, hermetically sealed to said anode at the open ends thereof, an energy absorbing meinber engaging each of said cavity resonators, and a conductor engaging said energy absorbing member and passing out of said device through a, bore in one of said electrically conductive pole pieces, said conductor and said electrically conductive pole piece constituting a transmission line.

WILLIAM C. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

'UNITED STATES PATENTS Number Name Date 2,154,758 Dallenbach Apr. 18, 1939 2,167,201 Dallenbach July 25, 1939 2,348,986 Linder May 16, 1944 2,408,235 Spencer Sept. 224, 1946 2,414,084 Bowen Jan. 14, 1947` 2,414,085 Hartman Jan. 14, 1947 FOREIGN PATENTS Number Country Date 509,102 Great Britain July 11, 1939 

